14 November 2020 | New Scientist | 13natural transmission, cell cultures
and computer modelling, the
researchers drafted a list of almost
60 mammal species that are
definitely, probably or possibly
susceptible, ranging from gorillas
and chimps to foxes, yaks, giant
pandas and koalas. Even some
whales, dolphins and seals may
be able to catch it.
“Yes, I was surprised by that,”
says Leendertz. However, he
points out that seals or sea lions
probably brought tuberculosis
to the Americas long beforeEuropeans arrived, “so it is not
totally impossible to have spillover
between marine mammals and
terrestrial ones”.
Leendertz and his colleagues
also recommended that anyone
at risk of coming into close contact
with a wild mammal should take
some now-familiar precautions:
physical distancing, wearing a face
mask and gloves, and frequent
hand washing. The list of people
who need to take such precautions
is a long one, including wildlife
researchers and conservationists,“Reverse spillover is
something we have to
keep an eye on. If we
can avoid it, we should”PUFF
IN’SPICTURE
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newscientist.com/healthcheckabsolutely necessary and never
blowing on a bat, which researchers
often do to examine its skin.
The IUCN has also issued
guidelines to cavers, bat guano
harvesters and bat rehab and
rescue centres. In a nutshell,
when possible, steer clear of bats.
Another country that
has no experience of bat
betacoronaviruses is Australia.
“To date, there is no evidence of any
SARS or MERS-like viruses in any
Australian bat species,” says Peel.
In August, she and her
colleagues carried out a risk
assessment for Australia’s
81 species of bat. It concluded
that the risk of reverse spillover
was low, but there were such
high levels of uncertainty that
it recommended that people
who know they are going to
come into contact with bats
should take precautions.Bat backlash
The assessment also concluded
that although the risk of
Australian bats being sickened
or killed by the virus are low, they
are vulnerable to a “bat backlash”
from humans spooked by the
virus. SARS-CoV-2 has already led
to politicians calling for bat culls
and people illegally persecuting
bats in Australia and elsewhere.
The report warns that one species
in Australia, the spectacled flying
fox, which provides ecosystem
services including pollination and
seed dispersal, could be driven to
local extinction this way.
The wildlife threat doesn’t begin
and end with bats. A recent review
by a team led by Fabian Leendertz
at the Robert Koch Institute in
Berlin concluded that a wide range
of distantly related mammals are
susceptible to SARS-CoV-2 (see
“Mammals at risk”, page 11).
Drawing on evidence frommanagers of protected areas,
foresters, pest controllers,
employees or volunteers in
wildlife rehabilitation centres
and wildlife tourism, and wildlife
tourists themselves.
The mink slaughter debate
has brought the wider issues of
reverse spillover and spillback
into the public consciousness.
How worried should we be?
“I think the risk is very small at
the moment because we are the
main reservoir of the virus and the
main drivers of the pandemic,”
says Leendertz. “But consider a
scenario where we have been able
to control the virus and push it out
of certain regions. Then you have
to start thinking about the risk of
reintroduction into the human
population from secondary
reservoirs in wild species. Reverse
spillover is something we have to
keep an eye on. If we can avoid it,
we should.”
The threats of reverse spillover
and spillback are teaching us
something profound. “We need to
change our interface with nature,”
says Leendertz. “Especially with
wild animals.” ❚Nadia, a Malayan tiger
at the Bronx Zoo in New
York, tested positive for
the coronavirus
A wild spectacled
flying fox in Kuranda,
Queensland, Australia